The advent of so-called X-ray lenses over two decades ago has prepared the ground for lightweight, portable X-ray devices with a broad spectrum of applications in areas as different as metallurgy, geology, chemistry, forensic laboratories and customs inspection. In a similar way as conventional optical lenses redirect visible or near-visible photons, X-ray lenses redirect electromagnetic radiation in the X-ray radiation band and may thus be used to collimate or focus a beam of X-rays.
An X-ray lens is conventionally formed from a plurality of capillaries. Each capillary guides the X-rays captured at a front end thereof to the opposite end by way of total external reflection. This rule applies so long as the angle of incidence at the front end does not exceed a critical angle. If the critical angle is exceeded, X-rays can no longer be captured within the capillary. In such a case, the capillary becomes transparent to the X-rays.
Originally, an X-ray lens was a bulky device with dimensions in the region of up to several meters. These large dimensions were mainly the result of separate support structures that were required to keep the individual capillaries in place. Commercial use of X-ray lenses became feasible when it was recognized that the support structures can be omitted if the X-ray lens is produced out of one or more glass capillary bundles using glass drawing techniques. By fusing the capillary mantles together, separate support structures became obsolete.
Today, the commercial application of X-ray lenses includes portable X-ray spectrometers, lightweight X-ray diffractometers and many other small-sized devices. Such devices typically comprise an X-ray source (such as an X-ray tube), an X-ray lens and a detector. X-rays emitted from the X-ray source are focused by the X-ray lens onto a tiny spot on a sample. The detector detects the X-rays emitted back from the sample and generates an output signal that can for example be spectrally analysed to determine the chemical elements included in the sample.
To enhance the efficiency of an X-ray device, the X-ray lens must be precisely aligned with respect to an axis of the X-ray device. If the X-ray lens is not correctly aligned, the flux of X-rays captured by the X-ray lens can get drastically reduced as a result of the fact that the angle of incidence exceeds the critical angle for too many X-rays.
In the past, the alignment of X-ray lenses was a cumbersome task even for very experienced operators. With conventional positioning mechanisms, the adjustment in one direction often involved a simultaneous (mis-)adjustment in another direction. These dependencies prevented an intuitive alignment of an X-ray lens and required many individual adjustment steps.
Accordingly, there is a need for a positioning apparatus and a positioning method that facilitate the adjustment of an X-ray lens. Also, there is a need for an X-ray device including a positioning apparatus for an X-ray lens.